Joint Injury Prevention in Foals

Developmental and traumatic joint injuries are a significant problem in Thoroughbred foals. These injuries, such as osteochondritis dissecans (OCD) and fetlock joint lesions, often require costly medical treatment or surgical repair. Polysulphated glycosaminoglycan (PSGAG), are commonly used to treat degenerative and traumatic joint diseases in performance horses medically, and in a recent study, researchers examined the preventative effects of PSGAGs on joint injuries in Thoroughbred foals. Using intramuscular injectable Adequan, researchers found that PSGAGs significantly reduced joint injuries in foals.

In 2004, Gary W. White, DVM, an Oklahoma practitioner, completed the first two-year phase of an ongoing four-year study, which evaluated the long-term use of PSGAG in 74 Thoroughbred foals born in 2003. He presented his findings at the 44th annual British Equine Veterinary Association Conference held in Harrogate, Yorkshire, England, in September 2005. The second phase of the study is underway to determine if PSGAG administered over a shorter period of time will produce similar results.

White used 233 untreated foals born on a Kentucky farm between 2000 and 2002 as a baseline for comparison (control group). In his study, he treated 74 foals between eight and 12 weeks old with twice-weekly PSGAG treatments. Foals received four weeks of treatment with alternating four-week intervals without treatment until age 1. Foals were then treated once weekly until November of the following year.

"The goal is to find a way to reduce the incidence and effects of developmental orthopedic diseases in foals in a cost-effective method, which could be widely applied in the industry," White said.

Cartilage in a foal's joint (growth plates) allows room for bone growth. As the foal matures, these growth plates are converted into bone. White describes OCD as "a failure of the growth plates to calcify. We don't know what triggers that."

Of the foals receiving PSGAG in the study, nine (12%) had OCD lesions compared to 38 (16%) from the control group, and one foal (1.4%) required surgery compared to 22 (9.4%) in the control group.

Fetlock joint lesions decreased from 30 incidents to two, and one foal required surgery to repair a lesion compared to 29 in the control group (about a 90% decrease). Foals used in the study showed no adverse reactions to the treatments.

"The mechanism underlying these benefits could be related to the modifying effects of the PSGAG on joint inflammation and cartilage injury," White explained. "The early results of PSGAG treatment are encouraging."

Polysulphated glycosaminoglycan is a polymer extracted from bovine tracheal tissue. The molecular structure of PSGAG is similar to that of cartilage matrix. Scientists believe the polymer binds to joint cartilage, specifically osteoarthritic cartilage. Binding of PSGAG and cartilage leads to reduced cartilage breakdown and increased synthesis of new cartilage. White explained that once the cartilage is completely lost, it can't be repaired.

Researchers have yet to determine how these effects are achieved, but the early results of PSGAG treatment are encouraging. White said, "Additional studies are underway to ascertain whether a shorter prophylactic treatment period will show similar results."